The pgstattuple function provides the following useful columns:
table_len: The length of the table.tuple_count: The number of tuples.tuple_len: The length of the tuples.dead_tuple_count: The number of dead tuples.dead_tuple_len: The length of dead tuples.free_space: The amount of free space.
Example
How you might use this function:
SELECT * FROM pgstattuple('gin_index_name');
Interpreting Results
- If the
dead_tuple_countis high relative to thetuple_count, this indicates bloat. - If
free_spaceis a significant portion oftable_len, the index may be bloated.
Using pg_trgm for Trigram Indexes
If you're using a GIN index with the pg_trgm extension (for trigram indexes), you might also consider analyzing the table and index sizes directly:
SELECT pg_size_pretty(pg_relation_size('table_name')) AS table_size, pg_size_pretty(pg_total_relation_size('table_name')) AS total_size, pg_size_pretty(pg_relation_size('gin_index_name')) AS index_size;
Vacuum and Reindex
If you determine that your GIN index is bloated, you can use VACUUM and REINDEX to reclaim space:
VACUUM ANALYZE your_table_name; REINDEX INDEX your_gin_index_name;
By following these steps, you should be able to detect and address bloat in your PostgreSQL GIN indexes effectively.
On Fri, Jul 26, 2024 at 8:01 AM Keith Fiske <keith.fiske@xxxxxxxxxxxxxxx> wrote:
On Thu, Jul 25, 2024 at 8:59 AM khan Affan <bawag773@xxxxxxxxx> wrote:Hello Kam FookYou can use pgstattuple extension, & you can use pg_trgm or gin_index_stats functions from the pgstattuple extension to check for bloat in GIN indexes.Thank & Regards
Muhammad Affan (아판)
PostgreSQL Technical Support Engineer / Pakistan R&D
On Thu, Jul 25, 2024 at 2:07 AM Wong, Kam Fook (TR Technology) <kamfook.wong@xxxxxxxxxxxxxxxxxx> wrote:This e-mail is for the sole use of the intended recipient and contains information that may be privileged and/or confidential. If you are not an intended recipient, please notify the sender by return e-mail and delete this e-mail and any attachments. Certain required legal entity disclosures can be accessed on our website: https://www.thomsonreuters.com/en/resources/disclosures.htmlI have a GIN index. Is there a way to detect if a postgres GIN index is bloated or not? The regular select * from pgstatindex(‘indexname’); does not work because the GIN index is not btree index.
Thank you
Any more insight on how to use those two options to actually calculate GIN bloat? From what I could tell pgstattuple didn't provide anything that could be used. I hadn't looked further into the other yet, but if you know how to do that already that info would be great.--
